Sunscreen formulation myths: putting the protection back in SPF

How sunscreen SPF is tested

Before we look at the fearmongering claims out there, let’s be clear about how SPF is tested:

• It is a legal requirement that any product put onto the market with a UV/sun protection or SPF claim must have a high level of evidence to support the statement. This is done in the consumers best interest – so they can make an informed decision about the SPF rating or protection offered by their product. Companies wanting to put sunscreen products onto the market need to hold this evidence specific to their product and formula to ensure consumers are getting the protection claimed on the label.
• sunscreen formulas need to be SPF tested in accordance with ISO 24444:2010. This standard is adopted in over 60 countries, including Australia, New Zealand, EU (28 countries), UK, India, Japan, Taiwan, Korea, MERCOSUR (6 countries), ASEAN (10 countries), South Africa, Mexico, Chile, Russia, Israel, India, Russia, Japan.
• sunscreen formulas are considered drugs in Canada and USA, and as such are subject to different, even stricter regulations.
• water resistance claims may be made up to 80 minutes in all the above listed countries (where evidence shows water resistance after required in vivo testing), except Australia and New Zealand where time limits may be higher, so long as the product achieves a minimum SPF rating, and in that case, must be tested according to the standard AS/NZS 2604:2012:

Finally, it is important to point out that SPF testing is conducted by applying 2mg of product per square centimeter of skin – that is equivalent to applying around 35grams of sunscreen product over a typical adult body to get the SPF protection claimed on a label. Most people would not apply anywhere near this amount of sunscreen, meaning they are already not getting the full protection rating from a product’s label unless they use 2mg of product per cm2! We have seen many reports where roll-on and spray-on products have left consumers red after a day in the sun – the extremely thin films of product that get applied using these methods should give you some understanding as to why the stated SPF is not achieved. The key message here: apply sunscreen products liberally to get the stated SPF protection!

Myth 1: Chemical sunscreen agents are estrogenic/more harmful than sun exposure

All sunscreen agents, whether chemical or physical, have been rigorously tested with strict regulatory limits over their use in formulas. When these regulations are complied with, they ensure consumer safety both from the ingredients used in sunscreen formulas, as well as consumer protection from harmful UV exposure. If there is ever a doubt or concern raised about a UV filter, country regulators are quick to explore the body of evidence and input rates to ensure ongoing consumer protection.

Think about it: the treatment of skin cancer and cancer in general costs country healthcare systems (and consumers) enormously - $824 million dollars in Australia alone in 20211! It is in the Government’s best interest, of all countries, to ensure safety of consumers when using sun protection products. They certainly don’t want to add to this figure by using chemicals with even the slightest increase of risk!

If you see claims suggesting UV filters are estrogenic or cause any sort of harm you should ignore them – especially since some of this fear mongering is created by companies advertising so called ‘natural’ sunscreen agents. Of course they want you to think chemical sunscreens are the bad guys – they’re trying to sell you a product which tends to cost more, is harder to stabilise and often feels tackier on the skin!  

Myth 2: Zinc oxide and titanium dioxide are natural

Despite their presence in certified organic and natural skincare products, zinc oxide and titanium dioxide are NOT natural. Contrary to popular belief, zinc oxide and titanium dioxide are not simple ‘mine it from the ground’ cosmetic ingredients. While suppliers of the materials often keep their processing methods proprietary, it involves at least a couple of chemical reactions, generally extreme heat, and various purification steps2.

Zinc oxide and titanium dioxide are subject to regulatory limits just like other UV filters. The one potential advantage they have in terms of protection is they provide physical protection: reflection of UV light, compared to the absorptive UV protection that so called ‘chemical’ UV filters provide.

Zinc oxide is also relatively broad spectrum – meaning it offers physical protection of the sun’s rays over a UVA and UVB wavelength. Broad spectrum wavelength protection usually requires the combination of several UV filters where zinc oxide is not used.

The downsides to zinc oxide and titanium dioxide are, because they are powders, they can be difficult to stabilise in cosmetic formulas and can feel very chalky or ‘drag’ on skin application – this can be improved by using high inputs of sensory enhancing esters or silicone materials, or combining a few different types of UV filters to get a synergistic effect (and overall lower input) and broad spectrum protection.

Myth 3: Sunscreen products can be made ‘reef safe’ by avoiding certain UV filters

To claim ‘reef safe’, it is more than just avoiding suspected sunscreen agents in your formula. To support the claim ‘reef safe’, you actually need to have the entire finished formulation tested by an appropriately validated method/testing facility, and show EITHER:

• water resistance to 4 hours both in vitro and in vivo. If it doesn’t wash off, then it can’t impact the reef systems OR
• all marine environment toxicity tests:
  • microalgae cell division
  • sea urchin larval development
  • fish larvae development

At this point in time, more research needs to be conducted to definitively prove or disprove if common sunscreens are causing issues to the coral reefs. To review how the current ‘science’ may have been misused, then popularized through government restrictions, refer to source 3: Toxic effects of UV filters from sunscreens on coral reefs revisited: regulatory aspects for “reef safe” products. This journal article is available free online, and provides a balanced, scientific review of how there is not sufficient information for governments to be making legislation just yet, and also demonstrates how zinc oxide is toxic to aquatic life but has been ‘overlooked’ in the legislation, because it is considered ‘natural’ (even though it is not).

In addition, there is an indepth environmental study provided as source 4: Review of Fate, Exposure, and Effects of Sunscreens in Aquatic Environments and Implications for Sunscreen Usage and Human Health. This study provides detail on degradation pathways, accumulation and other environmental impacts of various sunscreens from environmental testing, as well as the impact not using sunscreen can have on human health. It contains several recommendations where further research is needed to definitely prove or disprove the impact UV filters from sunscreens have on our aquatic environment.  

At this stage, it is also believed that climate change has a far more dramatic effect on corals than sunscreens; and the true impact of consumer use of sunscreens is still to be quantified in a real-world context, especially considering the volume of water vs. amount of sunscreen that gets used. Consider too the amount of other chemicals that enter our waterways, including oil spills from tankers, compared to the amount that can be introduced from people swimming or washing off their sunscreen in the shower.

The overarching principal is: if the product does not pass water resistance testing to at least 4 hours and/or pass marine environment toxicity tests specific to the formula then it should not claim ‘reef safe’ – regardless of the ingredients it does or does not use. Without this evidence, the claims are not justified and should not be made.

Myth 4: Natural plant oils can provide SPF protection

This myth is flat out dangerous to consumers health. Natural plant oils CANNOT provide sufficient UV protection, even when applied straight to the skin. You can see evidence of testing in this video: Natural oils and sun protection.

No plant oil has been able to pass required UV testing to provide an SPF rating for consumer use. It is dangerous to suggest a consumer can get sun protection from using natural plant oils as they do not provide anywhere near suitable protective benefits.

Learn to formulate tanning products

Nano-particles are a relatively new cosmetic innovation (within the last two decades) utilising particulate materials that are ≤100nm. Utilising zinc oxide in its nano form has been popular for sunscreen products because of its broad-spectrum coverage against damaging UVA and UVB rays without leaving an undesirable ‘ghosty’ white residue on the skin. Zinc oxide is also seen as a ‘greener’ ingredient choice than using chemical (organic) UV absorbers by many consumers.

However, its use has come under scrutiny from groups prone to scare-mongering due to the novelty of its nano-form despite the strong body of scientific evidence to show that nano zinc oxide is safe when used within current regulatory limits. It is also a requirement of all products marketed in the EU to indicate all nano-sized ingredients in the ingredient list – a regulatory requirement of all nano-particles that is misrepresented by scare-mongerers.

The most important and strongest body of evidence shows that nano-zinc oxide particles remain on the surface of the skin, and in any case, are unable to penetrate to living cells of the dermis^5,6. While the presence of zinc ions within the blood and urine may be related to the topical application of zinc oxide, there is a distinct difference between the presence of zinc ions and zinc oxide particulates. In any case, the study that showed an increase in zinc ion presence following topical zinc oxide exposure also showed the increase was negligible compared with levels of zinc normally found in the body or consumed through the average diet and thus unlikely to have any impact on human health^5,6

The use of in vitro studies on cell cultures, macrophages and other physiological processes to suggest an effect in humans under normal cosmetic usage conditions should be considered invalid as the results are void if the substance can’t actually penetrate the dermis⁶

Fact: sun exposure without protection can lead to skin cancer

Sun exposure without protection can lead to skin cancer, and this can be fatal. This is the one fact you can be certain of. You can also be certain that exposure to the sun without protection will cause advanced skin dryness and signs of ageing.

The only effective measures to protect yourself from harmful UV exposure is to cover up, avoid excess exposure where possible and use properly formulated and tested sunscreen products. If the brand has complied with all regulatory requirements regarding formulation and testing, then you are entitled to use your sunscreen product knowing it is safe and effective – just remember to apply liberally and repeatedly to get the stated SPF results.

Read an overview of how sunscreen formulas are put together here. Learn to formulate sunscreens properly, including all regulatory requirements, with our Certificate in Advanced Cosmetic Science or Diploma of Personal Care Formulation, or ensure your sunscreen products are formulated by a qualified Cosmetic Chemist and all compliance requirements are achieved.

Happy formulating!

References:

1 Gordon, Leung. et al. (2022). Estimated Healthcare Costs of Melanoma and Keratinocyte Skin Cancers in Australia and Aotearoa New Zealand in 2021. Int J Environ Res Public Health. 19(6): 3178. Accessed 7th April, 2023.

2 Kolodziejczak-Radzimska A & Jesionowski T. (2014). Zinc oxide – from synthesis to application: a review. Materials (Basel). 7(4): 2833 – 2881. Accessed 7th April, 2023.

3 Miller, I.B., Pawlowski, S., Kellermann, M.Y. et al. (2021). Toxic effects of UV filters from sunscreens on coral reefs revisited: regulatory aspects for “reef safe” products. Environ Sci Eur 33, 74. Accessed 7th April, 2023.

4 National Academies of Sciences, Engineering, and Medicine. 2022. Review of Fate, Exposure, and Effects of Sunscreens in Aquatic Environments and Implications for Sunscreen Usage and Human Health. Washington, DC: The National Academies Press. https://doi.org/10.17226/26381.

5 European Commission (2015). Opinion on Zinc Oxide (Nano-Form): Are sunscreens using zinc oxide nano particles safe? Accessed 7th April, 2023.

6 Therapeutic Goods Administration (2013). Literature review on the safety of titanium dioxide and zinc oxide nanoparticles in sunscreens. Accessed 7th April, 2023.